Three-dimensional annuloplasty ring

ABSTRACT

An annuloplasty ring having a three-dimensional discontinuous form generally arranged about an axis with two free ends that are axially offset. The ring is particularly suited for repair of the tricuspid valve, and more closely conforms to the annulus shape. The ring is more flexible in bending about radially extending axes than about the central axis. The ring may have an inner structural support covered by a pliable sleeve and/or a fabric tube. The structural support may have a varying cross-section, such as a C-shaped cross-section in a mid-section between two free ends and a rectangular cross-section at the free ends.

RELATED APPLICATIONS

The present application is a continuation of application Ser. No.11/106,421, filed Apr. 14, 2005 now U.S. Pat. No. 8,123,800, which is adivisional of application Ser. No. 10/139,070, filed May 3, 2002, nowU.S. Pat. No. 6,908,482.

FIELD OF THE INVENTION

The present invention relates generally to medical devices andparticularly to a tricuspid annuloplasty ring and delivery template.

BACKGROUND OF THE INVENTION

In vertebrate animals, the heart is a hollow muscular organ having fourpumping chambers: the left and right atria and the left and rightventricles, each provided with its own one-way valve. The natural heartvalves are identified as the aortic, mitral (or bicuspid), tricuspid andpulmonary, and are each mounted in an annulus comprising dense fibrousrings attached either directly or indirectly to the atrial andventricular muscle fibers.

Heart valve disease is a widespread condition in which one or more ofthe valves of the heart fails to function properly. Diseased heartvalves may be categorized as either stenotic, wherein the valve does notopen sufficiently to allow adequate forward flow of blood through thevalve, and/or incompetent, wherein the valve does not close completely,causing excessive backward flow of blood through the valve when thevalve is closed. Valve disease can be severely debilitating and evenfatal if left untreated.

Various surgical techniques may be used to repair a diseased or damagedvalve. In a valve replacement operation, the damaged leaflets areexcised and the annulus sculpted to receive a replacement valve.

Another less drastic method for treating defective valves is throughrepair or reconstruction, which is typically used on minimally calcifiedvalves. One repair technique that has been shown to be effective intreating incompetence is annuloplasty, in which the effective size ofthe valve annulus is contracted by attaching a prosthetic annuloplastyrepair segment or ring to an interior wall of the heart around the valveannulus. The annuloplasty ring is designed to support the functionalchanges that occur during the cardiac cycle: maintaining coaptation andvalve integrity to prevent reverse flow while permitting goodhemodynamics during forward flow. The annuloplasty ring typicallycomprises an inner substrate of a metal such as stainless or titanium,or a flexible material such as silicone rubber or Dacron cordage,covered with a biocompatible fabric or cloth to allow the ring to besutured to the heart tissue. Annuloplasty rings may be stiff orflexible, may be split or continuous, and may have a variety of shapes,including circular, D-shaped, C-shaped, or kidney-shaped. Examples areseen in U.S. Pat. Nos. 5,041,130, 5,104,407, 5,201,880, 5,258,021,5,607,471 and, 6,187,040 B1. Most annuloplasty rings are formed in aplane, with some D-shaped rings being bowed along their anterior orstraight side to conform to the annulus at that location.

The present application has particular relevance to the repair oftricuspid valve, which regulates blood flow between the right atrium(RA) and right ventricle (RV), although certain aspects may apply torepair of other of the heart valves.

The tricuspid valve 20 is seen in plan view in FIG. 1 and includes anannulus 22 and three leaflets 24 a, 24 b, 24 c (septal, anterior, andposterior, respectively) extending inward into the flow orifice definedby the annulus. Chordae tendineae 26 connect the leaflets to papillarymuscles located in the RV to control the movement of the leaflets. Thetricuspid annulus 22 is an ovoid-shaped fibrous ring at the base of thevalve that is less prominent than the mitral annulus, but slightlylarger in circumference. The septal leaflet 24 a is the site ofattachment to the fibrous trigone, the fibrous “skeletal” structurewithin the heart. The triangle of Koch 30 and tendon of Todaro 32provide anatomic landmarks during tricuspid valve repair procedures. Theatrioventricular (AV) node 34 is a section of nodal tissue that delayscardiac impulses from the sinoatrial node to allow the atria to contractand empty their contents first, and relays cardiac impulses to theatrioventricular bundle. In a normal heart rhythm, the sinoatrial nodegenerates an electrical impulse that travels through the right and leftatrial muscles producing electrical changes which is represented on theelectrocardiogram (ECG) by the p-wave. The electrical impulse thencontinues to travel through the specialized tissue of the AV node 34,which conducts electricity at a slower pace. This will create a pause(PR interval) before the ventricles are stimulated. Of course, surgeonsmust avoid placing sutures too close to or within the AV node 34.C-rings are good choices for tricuspid valve repairs because they allowsurgeons to position the break in the ring adjacent the AV node 34, thusavoiding the need for suturing at that location.

Despite numerous designs presently available or proposed in the past,there is a need for a tricuspid ring that more closely conforms to theactual shape of the tricuspid annulus.

SUMMARY OF THE INVENTION

The present invention provides an annuloplasty ring including a ringbody generally arranged about an axis and being discontinuous so as todefine two free ends. The ring body has a relaxed configurationfollowing a three-dimensional path such that the free ends are axiallyoffset from an annulus reference plane through a midpoint of the ringbody. In a preferred embodiment, the two free ends are axially offsetbetween about 2-15 mm. The annuloplasty ring is particularly adapted toreinforce the tricuspid annulus, and as such has a curvilinear anteriorside ending in one of the free ends, a curvilinear posterior side endingin the other of the free ends, and a relatively straight septal sideextending between the anterior and posterior sides. The posterior sideis shorter and has a smaller radius of curvature than the anterior side.

In accordance with one aspect of the present invention, the ring bodycomprises an inner structural support of multiple bands of elasticmaterial. A low friction material may be interposed between each twoadjacent bands to facilitate movement therebetween. The multiple bandsmay be embedded in a matrix of pliable material, preferably moldedsilicone. In one embodiment, there are two concentrically disposed bandsembedded in the matrix of pliable material. To facilitate bending aboutaxes that extend radially, each of the multiple bands of elasticmaterial may have a relatively wider radial dimension than its axialdimension.

Another aspect of the invention is an annuloplasty ring that comprises athree-dimensional ring body generally arranged about a central axis andbeing discontinuous so as to define two free ends, wherein the ring bodyhas a construction that renders it more flexible in bending at the twofree ends than in a midpoint thereof.

The annuloplasty ring body may comprise an inner structural supporthaving two free ends, a curvilinear anterior side ending in one of thefree ends, a relatively straight septal side ending in the other of thefree ends, and a curvilinear posterior side extending between theanterior and septal sides, wherein a majority of the posterior side liesgenerally in a plane perpendicular to the axis. The two free ends aredesirably both axially offset in the same direction from the plane.Also, the structural support may have a cross-section that changesaround its length. For example, the cross-section may be partly C-shapedin the posterior side, yet the two free ends are rectangular.

In accordance with a further aspect of the invention, the ring body maycomprise an inner structural support band surrounded by a pliablematrix, wherein the matrix includes a tubular inner portion thatsurrounds the band and an outer flange through which implantationsutures can pass. The outer flange may be curved so as to be convex onits outer surface. Preferably, the outer flange is connected to theinner tubular portion with a plurality of circumferentially spaced apartradial walls so as to create a celled structure.

A further aspect of the present invention provides an annuloplasty ringincluding a ring body generally arranged about the central axis andbeing discontinuous so as to define two free ends. The ring body has aconstruction that renders it more flexible in bending about axes thatextend radially from the central axis than about the central axisitself. The ring body may comprise an inner structural support ofmultiple bands of elastic material. A low friction material may beinterposed between each two adjacent bands. The multiple bands may beembedded a matrix of pliable material, preferably silicone. There may betwo concentrically disposed bands embedded in the matrix of pliablematerial. Desirably, each of the multiple bands elastic material has arelatively wider radial dimension than its axial dimension.

In a still further aspect of the present invention, an annuloplasty ringtemplate is provided. The template has a rigid body with a peripheralmounting ring generally arranged about an axis and being discontinuousso as to define two free ends. The mounting ring follows athree-dimensional path such that the free ends are axially offset. Thetemplate may include a central platform to which the peripheral mountingring is connected via a plurality of generally radially extendingspokes. A handle-receiving hub may extend generally away from centralplatform. Desirably, the peripheral mounting ring extends aboutthree-quarters circumferentially about the axis.

In a preferred embodiment, the peripheral mounting ring of the templatedefines a radially outward groove therein for receiving an annuloplastyring. The template further may include a plurality of cutting guidesprovided on the peripheral mounting ring. A pair of through holes in themounting ring are provided on either side of each cutting guide suchthat a length of suture may extend through or about an annuloplasty ringpositioned on the outside of the mounting ring, through one of theholes, over the cutting guide, through the other hole, and back into theannuloplasty ring. Each cutting guide may comprise a pair ofintersecting slots, one of the slots being shallower than the other andpositioned to receive a suture extending between the through holes. Thedeeper slot provides space into which a sharp instrument may extend tosever the suture at the cutting guide.

Further understanding of the nature and advantages of the invention willbecome apparent by reference to the remaining portions of thespecification and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of the tricuspid valve and surrounding anatomy;

FIG. 2 is a perspective view of an exemplary annuloplasty ring of thepresent invention illustrating its axially-spaced free ends;

FIG. 2A is a cross-sectional view of the exemplary annuloplasty ringtaken along line 2A-2A of FIG. 2;

FIG. 2B is a cross-sectional view similar to FIG. 2A of an annuloplastyring of the prior art;

FIGS. 2C-2E are cross-sectional views of alternative annuloplasty ringsof the present invention taken through the rings in the same location asline 2A-2A of FIG. 2;

FIG. 3 is a perspective view of a tricuspid valve and surroundinganatomy;

FIG. 4 is a plan view of the annuloplasty ring of FIG. 2 implantedaround the tricuspid valve;

FIG. 5 is a perspective view of exemplary annuloplasty ring, holdertemplate and delivery handle of the present invention;

FIG. 6 is a perspective view of the ring, template and handlecombination of FIG. 5 positioned above the tricuspid valve and showingan exemplary attachment method;

FIGS. 7A-7C are perspective and elevational views of a further exemplaryholder template of the present invention;

FIGS. 8A-8D are perspective, elevational and plan views of a rigid yetelastic inner structural support of an alternative annuloplasty ring ofthe present invention; and

FIGS. 9A-9C are sectional views through the structural support of FIGS.8A-8D, taken along the section lines indicated in FIG. 8B.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention provides a non-planar or three-dimensional (3D)annuloplasty ring that is shaped to conform to a 3D annulus. Somestudies show that the tricuspid valve has such a non-planar annulus, andthus the present invention is particularly suited for repair of thatvalve. Of course, other valves may in some patients have 3D annuluses,and the annuloplasty ring of the present invention may also have use inthose locations, if desired by the surgeon. Of course, all annuloplastyrings are three-dimensional to some extent, as they have across-sectional thickness. In the context of the present invention, anon-planar or three-dimensional annuloplasty ring has a nominalcross-sectional centerline that assumes a three-dimensional shape, or inother words does not lie in a single plane. Likewise, the exemplary ringof the present invention, as well as other shapes that may benefit fromthe features embodied herein, has a non-circular peripheral shape, butis shown having an axis. The term “axis” in reference to the illustratedring, and other non-circular or non-planar rings, refers the linethrough the ring that passes through the area centroid of the ring whenviewed in plan view. This “axis” can also be viewed as imaginary line ofblood flow within the valve orifice and thus within the ring whenimplanted therein.

It should be understood that the various constructional details of anyone embodiment herein may be transferred to another embodiment, even ifnot explicitly mentioned. For instance, the inner ring structuralsupport seen in FIGS. 8A-8D may be used in a ring that has a siliconesleeve and outer fabric covering as described elsewhere. Also, thetemplates 90 or 110 seen in FIGS. 5-7 may be adapted to conform to andhold the ring constructed using the inner ring structural support seenin FIGS. 8A-8D.

Despite numerous ring designs in the past, none has effectivelyaccommodated the shape of the tricuspid valve. Prior C-shaped rings(i.e., those with a break in continuity around the periphery) are formedin a plane. When implanted, a planar ring will tend to conform anon-planar annulus to its own shape because of its relative stiffness.Unfortunately, this may interfere with optimum performance of the“repaired” valve.

FIG. 2 illustrates an exemplary annuloplasty ring 40 of the presentinvention having a ring body 42 generally arranged about an axis 44 andbeing discontinuous so as to define two free ends 46 a, 46 b. FIG. 3shows a tricuspid valve 20 in perspective, and FIG. 4 shows theannuloplasty ring 40 in plan view after having been implanted orotherwise affixed to the tricuspid valve 20. When viewed in plan view,as seen in FIG. 4, the body 42 of the annuloplasty ring 40 defines arelatively straight septal side 50 a, a curvilinear posterior side 50 b,and a curvilinear anterior side 50 c. The posterior side 50 b is shorterand has a smaller radius of curvature than the anterior side 50 c.

Again, the axis 44 in FIG. 2 lies at the centroid of the ring or alongof the axis of blood flow through the ring 40 when implanted, and itwill be understood that the directions up and down are as viewed in thefigure. The ring 40 is designed to be implanted in a tricuspid annulussuch that blood will flow in the downward direction.

FIG. 2 illustrates an exemplary axial offset of the two free ends 46 a,46 b. Radial lines are shown from each free end 46 a, 46 b to thecentral axis 44. The distance A between the intersections of theseradial lines and the axis 44 represents the axial offset. The distance Amay vary depending on the patient, but is typically between about 2.0 mmand 15.0 mm. In this embodiment, the curvilinear anterior side 50 c liesgenerally in a plane all the way to the free end 46 a. Therefore,because the second free end 46 b drops below the main part of theanterior side 50 c, which generally defines an annulus reference planefor the ring and host annulus, then it is axially offset from the firstfree end 46 a. However, the first free end 46 a may not lie in theannulus reference plane, and may drop to the same elevation as thesecond free end 46 b. Either free end 46 a, 46 b may even be axiallyabove the annulus reference plane. In short, the ring 40 is designed tobe three-dimensional to conform to the native tricuspid annulus, andthose of skill in the art will recognize the number of possiblepermutations.

Although the annuloplasty ring 40 may be constructed in a number of waysas defined in the prior art, one particularly useful constructionincludes some relatively rigid yet elastic inner structural supportsurrounded by a pliable core material and a fabric cover. For example,as seen in FIG. 2A, the annuloplasty ring 40 may include an innerskeleton of multiple bands 60 of relatively rigid yet elastic materialsuch as Elgiloy surrounded by a suture-permeable core material 62 suchas silicone, and having an outer fabric cover 64. The multiple bands 60may be separated by plastic or other relatively low friction material(e.g., TEFLON) so as to be able to more easily flex with respect to oneanother. It will be noted by those of skill in the art that the multiplebands 60, which limit the flexibility of the ring 40, are alignedgenerally perpendicular to the axis 44 and thus the ring is leastflexible in bending about the axis. Desirably, the ring 40 of thepresent invention is more flexible in bending about axes along radiallines from the central axis 44. That is, for example, the free ends 46a, 46 b are more easily flexed up and down parallel to the axis thantoward or away from one another. There are a number of ways toaccomplish this flexibility orientation, as seen in FIGS. 2C-2E.

In contrast, FIG. 2B shows a cross-section of a ring 70 of the prior artthat has an inner skeleton of multiple bands 72 of relatively rigidmaterial such as Elgiloy surrounded by a suture-permeable core material74 such as silicone, with an outer fabric cover 76. In such priordevices, the bands 60 are oriented along or parallel to the axis 44, andthus are more flexible in bending about the central axis.

FIG. 2C shows a cross-section of an alternative ring of the presentinvention having a plurality of inner bands 78 embedded in a morepliable matrix 80 such as silicone. As before, the bands 78 aredesirably more rigid than the matrix 80 and provide structural supportto the annulus when implanted. The bands 78 are thin in the axialdimension, and wide in the radial direction, so as to provide thepreferred flexibility characteristics of the ring of the presentinvention. The bands 78 are shown spaced apart with matrix 80 materialtherebetween to enhance the aforementioned flexibility.

FIG. 2D illustrates a further embodiment in which there are twoconcentrically disposed structural bands 81 embedded in a matrix 82 ofpliable material. The bands 81 together create the desired flexibilitycharacteristics of the ring, as explained above, even if theirrespective cross-sections are square or circular. As seen, however, thebands 81 preferably have a larger radial than axial dimension whichcontributes to the flexibility of the ring about radial axes.

FIG. 2E shows a cross-section of a ring having a circular reinforcingband 83 surrounded by a pliable matrix 84. A tubular inner portion ofthe matrix 84 surrounds the band 83, while an outer wall or flange 85provides additional material through which implantation sutures canpass. In a preferred embodiment, the flange 85 is curved so as to beconvex on its outer surface, and is connected to the inner tubularportion with a plurality of circumferentially spaced apart radial walls86. A series of circumferential cells 87 is thus created between thewalls 86. The celled structure of the matrix 84 renders it soft andcompressible, which facilitates conformance of the ring to very unevenannuluses. A fabric covering (not shown) may also be used.

With reference again to FIGS. 2 and 3, the three-dimensional shape ofthe annuloplasty ring 40 is seen corresponding generally to the shape ofthe tricuspid annulus 22. The first free end 46 a registers with an areaadjacent the septal leaflet 24 a, to the anterior side of the AV node34. The second free end 46 b registers with an area adjacent the septalleaflet 24 a, but to the posterior side of the AV node 34. The secondfree end 46 b is axially offset with respect to the first free end 46 aas is the respective anatomical attachment areas. Therefore, theannuloplasty ring 40 closely conforms to the 3-D shape of the annulus22, and minimal distortion of the tissue occurs when attaching the ringthereto. Furthermore, the oriented flexibility of the ring 40facilitates the 3-D shape matching, between ring and tissue because thefree ends 46 a, 46 b may be easily flexed with respect to one anotheralong arcs that are generally parallel to the axis 44.

The annuloplasty ring 40 is seen in FIG. 4 implanted in the annulus 22using a plurality of sutures 88, although those of skill in the art willunderstand that there are other attachment means. The sutures 88 areevenly distributed around the ring body 42 and tied off to presentminimal surface roughness and reduce the chance of thrombi formingthereon. Again, the free ends 46 a, 46 b are shown on either side of theAV node 34, which minimizes the risk of damaging the sensitiveconduction system.

A preferred delivery template and method are also provided for thethree-dimensional annuloplasty ring 40 of the present invention. Withreference to FIGS. 5 and 6, the ring 40 is shown releasably secured to atemplate 90 that is in turn held at the distal end of a delivery handle92. The template 90 provides a suturing platform for the ring 40,maintaining its advantageous shape while being implanted. In thisregard, the template 90 includes a peripheral mounting ring 94 generallyarranged about an axis coincident with the axis 44 of the ring 40. Theperipheral mounting ring 94 is discontinuous so as to define two freeends 96 a, 96 b and generally follows a three-dimensional path such thatthe free ends are axially offset. Desirably, the three-dimensional pathof the peripheral mounting ring 94 is the same as that of theannuloplasty ring 40. Sutures (not shown) or other similar expedientreleasably secure the ring 40 to the template 90 to form the assemblyseen in FIG. 5. A hub 98 of the handle 92 may be releasably attached tothe template using sutures or quick-release clips or the like so thatthe handle may be removed during implantation for better visibility ofthe annulus.

FIG. 6 shows a step in an interrupted suture implant procedure. Afterexposing the annulus 22, the surgeon secures a plurality of individualsutures 100 around the annulus 22 in the locations that the sutures willbe arranged around the ring 40. The free ends of each suture 100 arethen passed through the corresponding positions in the suture-permeableouter portion of the ring 40, as seen at 102. After all of the sutures100 have been pre-threaded through the ring 40, the surgeon manipulatesthe ring using the handle 92 down the array of sutures and into positionin the annulus 22. The next steps that are not illustrated includesevering each suture close to the ring 40 and tying them off as seen inFIG. 4. Again, the handle 92 may be detached from the template 90 forthis operation. Finally, the template 90 is detached from the ring 40and removed with any attaching sutures from the operating site.

FIGS. 7A-7C are several perspective views of an exemplary template 110for use in implanting the ring 40 of the present invention. The template110 includes a peripheral mounting ring 112 connected to a centralplatform 114 via a plurality of spokes 116. The template 110 may beconstructed of a variety of materials, with a biocompatible plasticbeing preferred. Windows 117 exist between the spokes 116 for greatervisibility of the implant site. A handle-receiving hub 118 projectsupward from the platform 114 and generally defines a central axis 120 ofthe template 110. The mounting ring 112 extends approximatelythree-quarters around the axis 120 and terminates in two axially-spacedfree ends 122 a, 122 b.

In a preferred embodiment, the mounting ring 112 includes a radiallyoutwardly opening channel or groove 124, which is sized to have aboutthe same curvature as the ring 40, and thus snugly retains the ring 40in place around the template 90. The groove 124 is shallow so that amajority of the ring projects outward therefrom to facilitate exposureto the annulus and attachment thereto.

A plurality, preferably three, of cutting guides 126 projects axiallyupward from the mounting ring 112 at regular intervals around itsperiphery. The cutting guides 126 each include a first relatively deepslot 128 and a second shallower slot 130 crossing the first slot.Sutures (not shown) desirably fasten the ring 40 to the template, andextend across the cutting guides 126 for easy severability. A pluralityof passages 132 in the mounting ring 112 opening in the groove 124permit passage of sutures directly from the ring body 42 through themounting ring to the cutting guides 126. As seen best in FIG. 7A, thereare two such passages 132 on either side of each cutting guide 126. Thepassages 132 are desirably straight holes from the upper surface of themounting ring 112 that intersect and thus open to the concave groove124.

The overall shape of the mounting ring 112 is three-dimensional, asexplained above, with the two free ends 122 a, 122 b being axiallyspaced apart. The three-dimensional may be a gentle spiral, or othersimilar shape as dictated by the particular patient, or by arepresentative sample of patients. In the illustrated embodiment, and asbest seen in FIG. 7C, a majority of the mounting ring 112 lies in aplane, with one side that terminates in the second free end 122 b beingformed in a gentle curve or spiral so as to be axially spaced from thefirst free end 122 a. The annuloplasty ring is arranged on the mountingring 112 so that the portion that will lie adjacent the septal leaflet(see 24 a and 50 a in FIG. 4) extends along the spiral segment of themounting ring. In general, it is believed that many patients have arelatively planar tricuspid annulus around the anterior and posteriorsides, but a depressed septal side. The shape of the mounting ring 112thus mimics the presumed anatomical contour, and thus the ring can besewn into place without unduly distorting the annulus.

FIGS. 8A-8D illustrate an exemplary inner structural support 150 for atricuspid annuloplasty ring of the present invention. The structuralsupport 150 is ultimately is covered with one or more outer flexiblelayers as described above, and therefore the final ring body assumes theshape of the support. The structural support 150 may be made of arelatively rigid material yet elastic material such as Elgiloy.

When viewed in plan view, as seen in FIG. 8B, the structural support 150defines a relatively straight septal side 156 a ending in one of thefree ends 154 b, a curvilinear posterior side 156 b, and a curvilinearanterior side 156 c ending in the other of the free ends 154 a. Theposterior side 156 b is between the other two sides. As in the earlierembodiment, the posterior side 156 b is shorter and has a smaller radiusof curvature than the anterior side 156 c.

The structural support 150 is generally arranged about an axis 152 andis discontinuous so as to define two free ends 154 a, 154 b. A majorityof the structural support 150 is located generally in an annulusreference plane 151 (see FIG. 8D) perpendicular to the axis 152, and thetwo free ends 154 a, 154 b curve away from the plane so as to be offsettherefrom. The annulus reference plane 151 is defined as the plane thatis perpendicular to the axis 152 at the elevation of the tricuspidannulus. That elevation, in turn, is represented in the drawings by themidpoint of the anterior side 156 c, or at least the midpoint of thelarger cross-section portion thereof (as detailed below). FIG. 8Cillustrates a midpoint M in the anterior side 56 c that represents thenominal elevation of the host annulus. A perpendicular line to the axis152 intersects reference point R. The reference plane is thusperpendicular to the axis 52 through point R.

As seen best in FIG. 8D, the two free ends 154 a, 154 b are thus axiallyoffset from the reference plane 151 in the same direction, as well aseach other. Of course, the free ends 154 a, 154 b need not be axiallyoffset from each other as is shown, though the ring will still bethree-dimensional (that is, the ring is non-planar). For instance, oneor both of the free ends 154 a, 154 b may even curve upward above thereference plane 151. The particular three-dimensional configuration ismodeled to fit the natural shape of a tricuspid annulus, or at least toapproximate that shape as best as possible, and thus those with anunderstanding of the tricuspid annulus will realize that a variety ofshapes are possible.

With regard to FIGS. 8B and 9A-9C, the cross-sectional shape of thestructural support 150, at least along most of the anterior side 156 c,is designed so as to have more flexibility in bending at the free ends154 a, 154 b. FIG. 9A is a cross-section through the anterior side 156 cand shows a generally C-shaped cross-section with an outwardly-facinggroove 160 formed between an upper web 162 and a lower web 164, bothextending from an inner base portion 166. The upper web 162 extendsslightly farther radially outward than the lower web 164.

The cross-sectional shape of the structural support 150 changes alongits length, from the midpoint M to the free ends 154 a, 154 b. Thetransition between the cross-section at the middle of the anterior side156 c and the cross-sections at the two free ends 154 a, 154 b isgradual, and is reflected in FIGS. 9A-9C. The webs 162, 164 graduallydiminish in radial dimension until all that is left is the rectangularbase portion 166, as seen in FIG. 9C. Because at both free ends 154 a,154 b the radial dimension is smaller than the axial, the ends are moreflexible in bending about the central axis 152. It should be mentionedthat the properties of the inner ring structural support seen in FIGS.8A-8D may be attained with other structures, for example, with themultiple concentric bands as described above.

While the foregoing is a complete description of the preferredembodiments of the invention, various alternatives, modifications, andequivalents may be used. Moreover, it will be obvious that certain othermodifications may be practiced within the scope of the appended claims.

What is claimed is:
 1. A tricuspid annuloplasty ring sized andconfigured for attaching to an interior wall of and reinforcing thetricuspid annulus, comprising: a relatively rigid single piece innerbody defining an elongated path, the inner body generally arranged aboutan axis and being split and discontinuous so as to define two free endswith a break therebetween and no inner body therebetween, the inner bodyhaving, in plan view, a curvilinear anterior side terminating in one ofthe free ends, a relatively straight septal side terminating in theother of the free ends, and a curvilinear posterior side extendingbetween the anterior and septal sides, wherein the inner body is sizedto extend within and around the tricuspid valve annulus, and wherein theinner body has a radial cross-section that gradually changes around itslength and is radially enlarged in a mid-point in comparison to the twofree ends.
 2. The tricuspid annuloplasty ring of claim 1, wherein thecross-section through the mid-point of the inner body is generallyC-shaped.
 3. The tricuspid annuloplasty ring of claim 2, wherein theC-shaped cross-section at the mid-point of the inner body defines anoutwardly-facing groove between an upper web and a lower web, bothextending from an inner base portion.
 4. The tricuspid annuloplasty ringof claim 3, wherein the upper web extends slightly farther radiallyoutward than the lower web.
 5. The tricuspid annuloplasty ring of claim3, wherein the webs gradually diminish in radial dimension until allthat is left at the free ends is the inner base portion.
 6. Thetricuspid annuloplasty ring of claim 1, wherein the two free ends arerectangular in radial cross-section and are more flexible in bendingabout the axis than the mid-point of the inner body.
 7. The tricuspidannuloplasty ring of claim 1, wherein the two free ends are axiallyoffset from each other.
 8. The tricuspid annuloplasty ring of claim 7,wherein the two free ends are axially offset from each other by adistance of about 2-15 mm.
 9. The tricuspid annuloplasty ring of claim7, wherein a majority of the posterior side lies generally in areference plane perpendicular to the axis.
 10. The tricuspidannuloplasty ring of claim 9, wherein the two free ends are both axiallyoffset in the same direction from the reference plane.
 11. The tricuspidannuloplasty ring of claim 1, wherein the inner body is surrounded by apliable matrix, and wherein the matrix includes a tubular inner portionthat surrounds the inner body and an outer flange through whichimplantation sutures can pass.
 12. A tricuspid annuloplasty ring sizedand configured for attaching to an interior wall of and reinforcing thetricuspid annulus, comprising: a relatively rigid inner body defining anelongated path, the inner body generally arranged about an axis andbeing split and discontinuous so as to define two free ends with a breaktherebetween and no inner body therebetween, the inner body having, inplan view, a curvilinear anterior side terminating in one of the freeends, a relatively straight septal side terminating in the other of thefree ends, and a curvilinear posterior side extending between theanterior and septal sides, wherein the inner body is sized to extendwithin and around the tricuspid valve annulus, and wherein a length ofthe posterior side lies generally in a reference plane perpendicular tothe axis, and wherein in a relaxed, non-stressed state of the innerbody, both free ends curve away from the reference plane in the samedirection so as to be offset therefrom.
 13. The tricuspid annuloplastyring of claim 12, wherein the ring is adapted to be mounted at thetricuspid annulus such that direction of blood flow through the ring isdown and both free ends curve downward away from the reference plane.14. The tricuspid annuloplasty ring of claim 12, wherein the two freeends are axially offset from each other.
 15. The tricuspid annuloplastyring of claim 14, wherein the two free ends are axially offset from eachother by a distance of about 2-15 mm.
 16. The tricuspid annuloplastyring of claim 12, wherein the inner body has a radial cross-section isstiffer in bending in a mid-point in comparison to the two free ends.17. The tricuspid annuloplasty ring of claim 16, wherein thecross-section through the mid-point of the inner body is generallyC-shaped.
 18. The tricuspid annuloplasty ring of claim 17, wherein theC-shaped cross-section at the mid-point of the inner body defines anoutwardly-facing groove between an upper web and a lower web, bothextending from an inner base portion.
 19. The tricuspid annuloplastyring of claim 18, wherein the webs gradually diminish in radialdimension until all that is left at the free ends is the inner baseportion.
 20. The tricuspid annuloplasty ring of claim 12, wherein thetwo free ends are more flexible in bending about the axis than at amid-point of the inner body.
 21. The tricuspid annuloplasty ring ofclaim 20, wherein the two free ends are rectangular in radialcross-section.